• Journal of Marine Life Science
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• v.5 no.2
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• pp.35-42
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• 2020

17β-estradiol (E₂) is a natural hormone secreted by ovary, and continuously discharged from household and livestock wastewater into aquatic environment. Due to its strong estrogenic activity, it has adverse effects on development and reproduction in crustacean as an endocrine disrupting chemical. Although ecdysteroid signaling pathway play a key role in development in crustacean, little information on transcriptional modulation of ecdysteroid-related genes in response to E₂ is available in small crustacean. Here, we investigated the acute toxicity of E₂ to obtain 24-h LC_x values in the brackish water flea Diaphanosoma celebensis. Time-dependent expression patterns of seven ecdysteroid pathway - related genes (CYP314a1, EcRA, EcRB, USP, ERR, Vtg, VtgR) were further examined using quantitative real time reverse transcriptase polymerase chain reaction (qRT-PCR). As results, 24-h LC₅₀ and LC₁₀ values were 9.581 mg/l and 4.842 mg/l, respectively. The mRNA expression of CYP314a1, EcRA, USP, VtgR was significantly up-regulated at 12 or 24 h after exposure to E₂. These findings indicate that E₂ can affect their molting and reproduction by modulating the expression of ecdysteroid pathway - related in D. celebensis. This study will be useful for better understanding of molecular mode of action of endocrine disrupting chemicals on molting process in small crustacean.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.2
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• pp.127-136
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• 2019

Sweet sorghum (Sorghum bicolor L. Moench), compared to traditional crops, has been evaluated as a useful crop with high adaptability to the environment and various uses, but cultivation has not expanded owing to a lack of related research and information in Korea. This study was conducted to estimate heading date in 'Chorong' sweet sorghum based on climate data of the last 30 years (1989 - 2018) from six regions (Jeonju, Buan, Jeongup, Imsil, Namwon, and Jangsu) in Jellabuk Province. In addition, we compared the growth and quality factors by sowing date (April 10, April 25, May 10, May 25, June 10, June 25, and July 10) in 2018. Days from sowing to heading (DSH) increased to 107, 96, 83, 70, 59, 64, and 65 days in order of the sowing dates, respectively, and the average was 77.7 days. The effective accumulated temperature for heading date was $1,120.3^{\circ}C$. The mean annual temperature was the highest in Jeonju, followed in descending order by Jeongup, Buan, Namwon, Imsil, and Jangsu. The DSH based on effective accumulated temperature gradually decreased in all sowing date treatments in the six regions during the last 30 years. DSH of the six regions showed a negative relationship with mean temperature (sowing date to heading date) and predicted DSH ($R^2=0.9987**$) calculated by mean temperature was explained with a probability of 89% of observed DSH in 2017 and 2018. At harvest, fresh stem weight and soluble solids content were higher in the April and July sowings, but sugar content was higher in the May 10 ($3.4Mg{\cdot}ha^{-1}$) and May 25 ($3.1Mg{\cdot}ha^{-1}$) sowings. Overall, the April and July sowings were of low quality and yield, and there is a risk of frost damage; thus, we found May sowings to be the most effective. Additionally, sowing dates must be considered in terms of proper harvest stage, harvesting target (juice or grain), cultivation altitude, and microclimate.

• Journal of Climate Change Research
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• v.5 no.1
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• pp.1-12
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• 2014

With continued economic growth, Korea has seen an increase in the nighttime activities of its citizens as hours of activity have extended into night. There is an increasing trend in energy consumption related to citizens' nighttime activities. In order to analyze ideas for an efficient replacement of the power consumption of streetlights and for profit generation by applying grid-type solar systems, this study used an RETScreen model. Through energy analysis and cost analysis, the application benefit and viability of grid-type solar street light systems were analyzed. With analysis result of a total weekly power generation of 114 kWh via a grid-connected solar streetlight system, it was shown that the net present value of a grid-connected solar street light system is 155,362 KRW, which would mean a payback period of about 5.2 years, and as such, it was shown that profit could be generated after about 6 years. In addition, if the grid-connected solar power generation system proposed by this study is to be applied, it was shown that 401,935 KRW in profit could be generated after the 20-year useful life set for the solar system. In addition, the sensitivity analysis was performed taking into account the price fluctuations of SMP, maintenance. As a result, a payback period has increased by 1~2 years, and there were no significant differences. Because the most important factor that affect the economic analysis is the cost of supply certification of renewable energy, a stable sales and acquisition of this certification are very important. the Seoul-type Feed in Tariff(FIT) connected to other institutions will enable steady sales by confirming to purchase the certification for 12 years. Therefore, if those issues mentioned above are properly reflected, Central-grid PV system project will be able to perform well in the face of unfavorable condition of solar PV installation.

• Journal of Climate Change Research
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• v.5 no.2
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• pp.95-107
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• 2014

The 'Green Start Movement' is a practical movement of green living to efficiently reduce the greenhouse gases originating from non-industrial fields such as household, commerce, transportation, etc. for the 'materialization of a low carbon society through green growth (Low Carbon, Green Korea)'. When the new government took office, following the Lee Myeongbak Administration that had presented 'Low Carbon, Green Growth' as a national vision, it was required to set up the direction of the practical movement of green life to respond to climate change persistently and stably as well as to evaluate the performance of the green start movement over the past 5 years. A questionnaire survey was administered to a total of 265 persons including public servants, members of environmental and non-environmental NGOs, participants of the green start movement and professionals. In the results of the questionnaire survey, many opinions have indicated that the awareness of the green start movement is increasing and the green start movement has had a positive impact on individual behavior and group behavior in terms of green living. The result shows, however, that the environmental NGOs don't cooperate sufficiently to create a 'green living' effect on a national scale. Action needs to be taken on the community level in order to generate a culture of environmental responsibility. The national administration office of the Green Start Movement Network should play the leading role between the government and environmental NGOs. The Green Start National Network should have greater autonomy and governance of the network needs to be restructured in order to work effectively. Also the Green Start Movement should identify specific local characteristics to support activities that reduce greenhouse gas emissions. Best practices can be shared to reduce greenhouse gas emissions by a substantial amount.

• Particle and aerosol research
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• v.15 no.1
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• pp.37-44
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• 2019

It is recommended for the public to stay at home and to close the doors and windows when a high-particulate-matter environment such as a yellow sand event occurs outside. However, there are lack of empirical studies describing how much outdoor PM infiltrates into a closed house and how much indoor PM an inhabitant is exposed to during the period. In this study, the $PM_{10}$ and $PM_{2.5}$ were measured at the kitchen in an apartment house by an optical particle counter for 3 days including a yellow sand event. The outdoor PMs and the outdoor wind speeds were referred from surrounding weather stations. We analyzed the penetration of $PM_{10-2.5}$ and $PM_{2.5}$ at the test house against the outdoor wind speed supposed corresponding to the change of air exchange rate. In addition, the effect of an indoor activity on change in the indoor PM was investigated. In result, the indoor $PM_{10-2.5}$ was very low even a yellow sand event occurred outside; rather, a contribution of indoor activities to increase in $PM_{10-2.5}$ was higher. In contrast, the indoor $PM_{2.5}$ fluctuated following the outdoor $PM_{2.5}$ trend at high wind speeds or remained almost constant at low wind speed.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.3
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• pp.158-169
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• 2019

A probabilistic model that can predict the residual useful lifetime of structure is formulated by using the gamma process which is one of the stochastic processes. The formulated stochastic model can take into account both the sampling uncertainty associated with damages measured up to now and the temporal uncertainty of cumulative damage over time. A method estimating several parameters of stochastic model is additionally proposed by introducing of the least square method and the method of moments, so that the age of a structure, the operational environment, and the evolution of damage with time can be considered. Some features related to the residual useful lifetime are firstly investigated into through the sensitivity analysis on parameters under a simple setting of single damage data measured at the current age. The stochastic model are then applied to the rubble-mound breakwater straightforwardly. The parameters of gamma process can be estimated for several experimental data on the damage processes of armor rocks of rubble-mound breakwater. The expected damage levels over time, which are numerically simulated with the estimated parameters, are in very good agreement with those from the flume testing. It has been found from various numerical calculations that the probabilities exceeding the failure limit are converged to the constraint that the model must be satisfied after lasting for a long time from now. Meanwhile, the expected residual useful lifetimes evaluated from the failure probabilities are seen to be different with respect to the behavior of damage history. As the coefficient of variation of cumulative damage is becoming large, in particular, it has been shown that the expected residual useful lifetimes have significant discrepancies from those of the deterministic regression model. This is mainly due to the effect of sampling and temporal uncertainties associated with damage, by which the first time to failure tends to be widely distributed. Therefore, the stochastic model presented in this paper for predicting the residual useful lifetime of structure can properly implement the probabilistic assessment on current damage state of structure as well as take account of the temporal uncertainty of future cumulative damage.

• Korean Journal of Environmental Biology
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• v.37 no.1
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• pp.19-30
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• 2019

To investigate the characteristics of seasonal environment and phytoplankton community structure in the coastal area of Dokdo, a survey of Dokdo around waters was conducted during the four seasons. Phytoplankton of 4 phylum 72 species in four seasons were collected in Dokdo around water. The seasonal mean abundance of phytoplankton were $3.32{\times}10^4cells\;L^{-1}$ in winter, $1.04{\times}10^4cells\;L^{-1}$ in spring, $0.28{\times}10^4cells\;L^{-1}$ in summer, and $4.86{\times}10^4cells\;L^{-1}$ in autumn in Dokdo around water. During winter, the diatoms Chaetoceros spp. had dominated. During spring, when the nutrients in the euphotic layer were depleted, the nano-flagellates and Cryptomonas appeared at surface layer. In summer, the abundance of phytoplankton was relatively low, which lead to occurrence of diatoms such as genus of Chaetoceros, Rhizosolenia, and Skeletonema. In autumn, Pseudo-nitzschia spp. was the most dominant species and tropical species such as Amphisolenia sp. and Ornithocercus magnificus were observed, implying that they may have introduced within warm water current such as Kurosiwo Current. Therefore, although natural phytoplankton communities in the vicinity water of Dokdo are mainly influenced by Tsushima Warm Current branched Kurosiwo Current, their population dynamics was affected on the spatio-temporal change of physicochemical factors by short-term wind events, namely "island effect". Long-term survey research is needed to facilitate food-web response in marine ecosystem associated with phytoplankton biomass and physicochemical factors including the warm water current in oligotrophic offshore water of Dokdo, which may have significant role for sustainable use of Dokdo.

• Clean Technology
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• v.25 no.3
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• pp.231-237
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• 2019

The BOD removal efficiency according to HRT of the continuous inflow SBR process was decreased from 92.1 ~ 96.0% at HRT 9 ~ 15 h to 86.9 ~ 90.7% at HRT 6 h, but a stable removal efficiency was shown up to HRT 6 h. The T-N removal rate was decreased to 80.1 ~ 87.9% at HRT 12 ~ 15 h, to 71.9 ~ 87.0% at HRT 9 h, and to 60.1 ~ 65.7% at HRT 6 h. As a result of the test of removing organic matter and nitrogen, the optimum HRT of the continuous inflow SBR reactor is determined as 9 h. The TCODcr removal efficiency was 88.4 ~ 96.0% and the TBOD removal efficiency was 92.1 ~ 98.1% as a result of examination of organic matter removal efficiency according to a change in the recycling rate (1 ~ 5Q) at HRT 9 h, suggesting that the a change in the recycling rate has a minimal effect on the removal of organic matter. The T-N removal efficiency was 70.3 ~ 80.4% at 1 ~ 2Q, 77.2 ~ 85.6% at 3Q and 61.5 ~ 80.8% at 4 ~ 5Q according to a change in the recycling rate. The TP removal efficiency was reduced to 75.0 ~ 84.6% at 1 ~ 4Q and to 63.3 ~ 72.4% at 5Q. This is presumably because the release and ingestion of phosphorus (P) by microorganisms is not performed smoothly at 5Q or more. Therefore, the optimum recycling rate for removing organic matter and nutrients was found to be 3Q.

• Korean Journal of Remote Sensing
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• v.35 no.3
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• pp.347-358
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• 2019

Lambertian cloud model (Lambertian Cloud Model) is the simplified cloud model which is used to effectively retrieve the vertical ozone distribution of the atmosphere where the clouds exist. By using the Lambertian cloud model, the optical characteristics of clouds required for radiative transfer simulation are parametrized by Optical Centroid Cloud Pressure (OCCP) and Effective Cloud Fraction (ECF), and the accuracy of each parameter greatly affects the radiation simulation accuracy. However, it is very difficult to generalize the vertical ozone error due to the OCCP error because it varies depending on the radiation environment and algorithm setting. In addition, it is also difficult to analyze the effect of OCCP error because it is mixed with other errors that occur in the vertical ozone calculation process. This study analyzed the ozone retrieval error due to OCCP error using two methods. First, we simulated the impact of OCCP error on ozone retrieval based on Optimal Estimation. Using LIDORT radiation model, the radiation error due to the OCCP error is calculated. In order to convert the radiation error to the ozone calculation error, the radiation error is assigned to the conversion equation of the optimal estimation method. The results show that when the OCCP error occurs by 100 hPa, the total ozone is overestimated by 2.7%. Second, a case analysis is carried out to find the ozone retrieval error due to OCCP error. For the case analysis, the ozone retrieval error is simulated assuming OCCP error and compared with the ozone error in the case of PROFOZ 2005-2006, an OMI ozone profile product. In order to define the ozone error in the case, we assumed an ideal assumption. Considering albedo, and the horizontal change of ozone for satisfying the assumption, the 49 cases are selected. As a result, 27 out of 49 cases(about 55%)showed a correlation of 0.5 or more. This result show that the error of OCCP has a significant influence on the accuracy of ozone profile calculation.

• Journal of the Mineralogical Society of Korea
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• v.32 no.1
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• pp.41-49
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• 2019

Probing the Na environments in Na silicate and aluminosilicate glasses is essential to the macroscopic properties of melts in the Earth. In particular, exploring the atomic structure of Na silicate and aluminosilicate glasses reveals Na-O distance, which plays an important role in transport properties of melts. Here we report the local environment around Na using $^{23}Na$ magic angle spinning (MAS) NMR. We also obtain $^{23}Na$ isotropic chemical shift (${\delta}_{iso}$) of Na silicate and aluminosilicate glasses with varying composition using Dmfit program. The Q mas 1/2 model simulates the experimental results with three simulated peaks while the CzSimple model simulates with one peak. The ${\delta}_{iso}$ decreases with increasing $SiO_2$ content in Na silicate and aluminosilicate glasses. The ${\delta}_{iso}$ increases with increasing $Na_2O$ content in Na-Ca silicate and Na aluminosilicate glasses when the $SiO_2$ content is fixed. Considering the ${\delta}_{iso}$ of Na aluminosilicate glasses available in the previous studies, together with the current simulation results, we confirm that the ${\delta}_{iso}$ has positive correlation with Al / (Al + Si). Those experimental results were reproduced better using Q mas 1/2 model. The disorder of Na in Na silicate and aluminosilicate glasses can be revealed through the simulation of 1D $^{23}Na$ MAS NMR spectra using Dmfit program in a short time.